A large number of current sensors and devices for measuring current are known from the state of the art. U.S. Pat. No. 7,545,136 discloses a device for current measurement which is suitable for the measurement of currents up to typically 100 A that can be loaded temporarily with an overload current of up to 1000 A and is shielded against external magnetic interference fields. CH 696859 and JP 62098267 disclose current sensors in which a first Hall sensor is arranged in the air gap of a yoke made of ferromagnetic material which encloses the current conductor, and a second Hall sensor is arranged outside of the yoke. The yoke and the first Hall sensor are used for measuring relatively small currents; the second Hall sensor is used for measuring relatively large currents. It is disadvantageous in these latter current sensors that the air gap is relatively large with typically 1 to 3 mm, the yoke requires a lot of material, and production and mounting is complex.